mm: change vunmap to tear down huge KVA mappings

Change vunmap_pmd_range() and vunmap_pud_range() to tear down huge KVA
mappings when they are set.  pud_clear_huge() and pmd_clear_huge() return
zero when no-operation is performed, i.e.  huge page mapping was not used.

These changes are only enabled when CONFIG_HAVE_ARCH_HUGE_VMAP is defined
on the architecture.

[akpm@linux-foundation.org: use consistent code layout]
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Robert Elliott <Elliott@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 14 insertions, 0 deletions

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 9fb7dc7ca7f4..39f1d6a2b04d 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -700,6 +700,8 @@ static inline int pmd_protnone(pmd_t pmd)
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot);
 int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot);
+int pud_clear_huge(pud_t *pud);
+int pmd_clear_huge(pmd_t *pmd);
 #else   /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
 static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
 {
@@ -709,6 +711,14 @@ static inline int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
 {
         return 0;
 }
+static inline int pud_clear_huge(pud_t *pud)
+{
+        return 0;
+}
+static inline int pmd_clear_huge(pmd_t *pmd)
+{
+        return 0;
+}
 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
 
 #endif /* !__ASSEMBLY__ */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a48cd061f16f..a5bbdd3b5d67 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -75,6 +75,8 @@ static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)
         pmd = pmd_offset(pud, addr);
         do {
                 next = pmd_addr_end(addr, end);
+                if (pmd_clear_huge(pmd))
+                        continue;
                 if (pmd_none_or_clear_bad(pmd))
                         continue;
                 vunmap_pte_range(pmd, addr, next);
@@ -89,6 +91,8 @@ static void vunmap_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end)
         pud = pud_offset(pgd, addr);
         do {
                 next = pud_addr_end(addr, end);
+                if (pud_clear_huge(pud))
+                        continue;
                 if (pud_none_or_clear_bad(pud))
                         continue;
                 vunmap_pmd_range(pud, addr, next);